The present invention pertains generally to formed wire structures and, more particularly, to machinery for automated manufacture and assembly of wire form structures such as coils and springs, and innerspring assemblies having an array of interconnected wire springs or coils.
Innerspring assemblies, for mattresses, furniture, seating and other resilient structures, were first assembled by hand by arranging coils or springs in a matrix and interconnecting them with lacing or tying wires. The coils are connected at various points along the axial length, according to the innerspring design. Machines which automatically form coils have been mated with various conveyances which deliver coils to an assembly point. For example, U.S. Pat. Nos. 3,386,561 and 4,413,659 describe apparatus which feeds springs from an automated spring former to a spring core assembly machine. The spring or coil former component is configured to produce a particular coil design. Coils are produced from steel wire stock which is fed through a die and bent or coiled at designed radiuses by cam-controlled forming guides. Following the helical formation of the coil in this manner, the heads or end turns of the coils may be secondarily formed by punch dies. Most coil designs terminate at each end with one or more turns in a single plane. This simplifies automated handling of the coils, such as conveyance to an assembler and passage through the assembler. Coil forming machinery of the prior art is not configured or easily adapted to produce coils of alternate configurations, such as coils which do not terminate in a single plane.
The timed conveyance of coils from the former to the assembler is always problematic. Automated production is interrupted if even a single coil is misaligned in the conveyor. The conveyor drive mechanism must be perfectly timed with operation of the coil former and a transfer machine which picks up an entire row of coils from a conveyor and loads it into the innerspring assembler.
The spring core assembly component of the prior art machines is typically set up to accommodate one particular type of spring or coil. The coils are held within the machine with the base or top of the coil fit over dies or held by clamping jaws, and tied or laced together by a helical wire or fastening rings. This approach is limited to use with coils of particular configurations which fit over the dies and within the helical lacing and knuckling shoes. Such machines are not adaptable to use with different coil designs, particularly coils with a terminal convolution which extends beyond a base or end of the coil. Also, these types of machines are prone to malfunction due to the fact that two sets of clamping jaws, having multiple small parts and linkages moving at a rapid pace, are required for the top and bottom of each coil.
The present invention overcomes these and other disadvantages of the prior art by providing novel machinery for complete automated manufacture of formed wire innerspring assemblies from wire stock. In accordance with one particular aspect of the invention, there is provided: a coil formation device for forming coils having a generally helical coil body, a non-helical coil head, and a terminal convolution generally smaller than the coil body, the coil formation device having a wire feed mechanism which feeds wire stock into a coil forming block, the coil forming block having a cavity within which a terminal convolution of the coil is formed, a coil radius forming wheel against which wire stock bears to form a generally helical shape to the coil body, a helical guide pin in contact with the wire stock and operative to move relative to the forming block to form a generally helical shape to the coil body, a wire cutting tool configured to cut the wire stock within the cavity of the coil forming block, a geneva for transferring a coil from the coil forming block to a coil head forming station, the coil head forming station having a coil head formation die, the coil head formation die having a cavity configured to receive a terminal convolution of the coil, and a flange proximate to the cavity about which an end turn of the coil body is positioned by the geneva, and at least one punch operative to strike the end turn of the coil body against the flange of the coil head formation die to form a coil head between the coil body and the terminal convolution.
In accordance with another particular aspect of the invention, there is provided: a coil head formation die for use with a coil forming machine for forming a coil head in an end turn of a body of a coil having a terminal convolution contiguous with a body of the coil, the coil head formed by operation of one or more punches of the coil forming machine operative to strike a portion of the end turn of the coil against the die while the end turn of the coil and the terminal convolution of the coil are engaged with the coil head formation die, the coil head formation die having a cavity configured to receive a terminal convolution of the coil, and a portion configured to oppose a punch which strikes the end turn of the coil to form a coil head.
And in another aspect of the invention, there is provided: an automated innerspring assembly system for producing innerspring assemblies having a plurality of wire form coils interconnected in an array, the automated innerspring assembly system having at least one coil formation device operative to form wire stock into individual coils configured for assembly in an innerspring assembly, and operative to deliver individual coils to a coil conveyor, a coil conveyor associated with the coil formation device and operative to receive coils from the coil formation device and convey coils to a coil transfer machine, a coil transfer machine operative to remove coils from the coil conveyor and present coils to an innerspring assembler, an innerspring assembler operative to receive and engage a plurality of coils arranged in a row, to position a received row of coils parallel and closely adjacent to a previously received row of coils, to fixedly compress two adjacent rows of coils in a fixed position and interconnect the adjacent rows of coils with fastening means, and to advance interconnected rows of coils out of the assembler and receive and engage a subsequent row of coils, and repeat the process until an entire innerspring assembly is formed.